Stented heart valve devices and methods for atrioventricular valve replacement

ABSTRACT

A compressible and expandable stent assembly for implantation in a body lumen such as a mitral valve, the stent assembly including at least one stent barrel that is shaped and sized so that it allows for normal operation of adjacent heart structures. One or more stent barrels can be included in the stent assembly, where one or more of the stent barrels can include a cylinder with a tapered edge.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationNo. 60/881,351, filed Jan. 19, 2007, and titled “Stented Heart ValveDevices and Methods for Atrioventricular Valve Replacement”, the entirecontents of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates generally to devices and methods forrepair of heart valves, and more particularly to prosthetic heart valvesfor use in replacement of the mitral valve.

BACKGROUND

One of the two atrio-ventricular valves in the heart is the mitralvalve, which is located on the left side of the heart and which forms ordefines a valve annulus and valve leaflets. The mitral valve is locatedbetween the left atrium and the left ventricle, and serves to directoxygenated blood from the lungs through the left side of the heart andinto the aorta for distribution to the body. As with other valves of theheart, the mitral valve is a passive structure in that it does notitself expend any energy and does not perform any active contractilefunction.

The mitral valve includes two moveable leaflets that open and close inresponse to differential pressures on either side of the valve. Ideally,the leaflets move apart from each other when the valve is in an openposition, and meet or “coapt” when the valve is in a closed position.However, problems can develop with valves, which can generally beclassified as either stenosis, in which a valve does not open properly,or insufficiency (also called regurgitation), in which a valve does notclose properly. Stenosis and insufficiency may occur concomitantly inthe same valve. The effects of valvular dysfunction vary, with mitralregurgitation or backflow typically having relatively severephysiological consequences to the patient. Regurgitation, along withother abnormalities of the mitral valve, can increase the workloadplaced on the heart. The severity of this increased stress on the heartand the patient, and the heart's ability to adapt to it, determine thetreatment options that are available for a particular patient. In somecases, medication can be sufficient to treat the patient, which is thepreferred option when it is viable; however, in many cases, defectivevalves have to be repaired or completely replaced in order for thepatient to live a normal life.

One situation where repair of a mitral valve is often viable is when thedefects present in the valve are associated with dilation of the valveannulus, which not only prevents competence of the valve but alsoresults in distortion of the normal shape of the valve orifice.Remodeling of the annulus is central to these types of reconstructiveprocedures on the mitral valve. When a mitral valve is repaired, theresult is generally a reduction in the size of the posterior segment ofthe mitral valve annulus. As a part of the mitral valve repair, theinvolved segment of the annulus is diminished (i.e., constricted) sothat the leaflets may coapt correctly on closing, and/or the annulus isstabilized to prevent post-operative dilatation from occurring. Eitherresult is frequently achieved by the implantation of a prosthetic ringor band in the supra annular position. The purpose of the ring or bandis to restrict, remodel and/or support the annulus to correct and/orprevent valvular insufficiency. Such repairs of the valve, whentechnically possible, can produce relatively good long-term results.

However, valve repair is sometimes either impossible or undesirable orhas failed, such as in cases where dilation of the valve annulus is notthe problem, leaving valve replacement as the preferred option forimproving operation of the mitral valve. In cases where the mitral valveis replaced, the two general categories of valves that are available forimplantation are mechanical valves and bioprosthetic or tissue valves.Mechanical valves have been used for many years and encompass a widevariety of designs that accommodate the blood flow requirements of theparticular location where they will be implanted. Although the materialsand design features of these valves are continuously being improved,they do increase the risk of clotting in the blood stream, which canlead to a heart attack or stroke. Thus, mechanical valve recipients musttake anti-coagulant drugs for life to prevent the potential of bloodclots. Further, mechanical valves can sometimes suffer from structuralproblems that may force the patient to have additional surgeries forfurther valve replacement. On the other hand, the use of tissue valvesprovides the advantage of not requiring anti-coagulant drugs, althoughtissue valves do not typically last as long as mechanical valves. Thus,tissue valves may wear out and need to be replaced after a number ofyears. The surgical procedure for implantation of many of thesemechanical and tissue valves typically involves opening the patient'schest to access the mitral valve through the left atrium, and sewing thenew valve in position.

To simplify surgical procedures and reduce patient trauma, there hasbeen a recent increased interest in minimally invasive and percutaneousreplacement of cardiac valves. Replacement of a heart valve typicallydoes not involve actual physical removal of the diseased or injurednative heart valve. Rather, the replacement valve is delivered in acompressed condition to the native valve site, where it is expanded. Oneexample of such a valve replacement system includes inserting areplacement pulmonary valve into a balloon catheter and delivering itpercutaneously via the vascular system to the location of a failedpulmonary valve. There, the replacement valve is expanded by a balloonto compress the native valve leaflets against the right ventricularoutflow tract, thereby anchoring and sealing the replacement valve. Inthe context of percutaneous pulmonary valve replacement, U.S. PatentApplication Publication Nos. 2003/0199971 A1 and 2003/0199963 A1, bothfiled by Tower, et al., describe a valved segment of bovine jugularvein, mounted within an expandable stent, for use as a replacementpulmonary valve. As described in the articles: “Percutaneous Insertionof the Pulmonary Valve”, Bonhoeffer, et al., Journal of the AmericanCollege of Cardiology 2002; 39: 1664-1669 and “Transcatheter Replacementof a Bovine Valve in Pulmonary Position”, Bonhoeffer, et al.,Circulation 2000; 102: 813-816, the replacement pulmonary valve may beimplanted to replace native pulmonary valves or prosthetic pulmonaryvalves located in valved conduits. Other implantables and implantdelivery devices also are disclosed in published U.S. Patent ApplicationPublication No. 2003/0036791 A1 and European Patent Application No. 1057 460-A1.

There is a continued desire to be able to be able to improve mitralvalve replacement devices and procedures to accommodate the physicalstructure of the heart without causing undue stress to the patientduring the operation on the heart, such as providing devices and methodsfor replacing the mitral valve percutaneously.

SUMMARY

One embodiment of the invention includes a compressible and expandablestent assembly for implantation in a body lumen. The stent assemblycomprises a first stent barrel comprising a tubular structure that iscompressible and expandable in a radial direction and that comprises anouter surface having a periphery, wherein a first portion of theperiphery of the first stent barrel has a first length and a secondportion of the periphery of the first stent barrel has a second lengththat is less than the first length, and further wherein the first stentbarrel comprises a tapered edge that extends from the first portion ofthe periphery of the first stent barrel to the second portion of theperiphery of the first stent barrel. Thus, the first stent barrelessentially includes a sloped surface between the first and secondportions of the stent barrel when the stent is viewed from the side. Thestent assembly further includes a second stent barrel adjacent to andextending from the first stent barrel, wherein the second stent barrelcomprises a tubular structure that is compressible and expandable in aradial direction and that comprises an outer surface having a periphery,wherein a first portion of the periphery of the second stent barrel hasa first length and a second portion of the periphery of the second stentbarrel has a second length that is less than the first length, andfurther wherein the second stent barrel comprises a tapered edge thatextends from the first portion of the periphery of the second stentbarrel to the second portion of the periphery of the second stentbarrel. Again, the second stent barrel essentially includes a slopedsurface between the first and second portions of the stent barrel whenthe stent is viewed from the side.

Another embodiment of the invention includes a compressible andexpandable stent assembly for implantation in a body lumen, wherein thestent assembly comprises a first stent barrel comprising a first lengthand a tubular structure that is compressible and expandable in a radialdirection and a second stent barrel comprising a second length that isless than the first length and a tubular structure that is compressibleand expandable in a radial direction, wherein the second stent barrel isadjacent to and extends from the first stent barrel along a tangentialline that extends in a generally perpendicular direction to the radialexpansion direction of the first and second stent barrels.

The invention further includes a method of positioning a stent assemblyinto the mitral valve area of a patient, the method comprising the stepsof providing a stent assembly comprising a first stent barrel having anouter peripheral surface and a first length, and a second stent barrelhaving an outer peripheral surface that is adjacent to and extendingfrom the outer peripheral surface of the first stent barrel, wherein thesecond stent barrel has a second length that is greater than the firstlength, and positioning the stent assembly in the mitral valve area sothat the first stent barrel is adjacent to an anerolateral portion ofthe mitral valve and the second stent barrel is adjacent to aposteromedial portion of the mitral valve, wherein the length of thefirst stent barrel minimizes interference with the functioning of anadjacent aortic valve and provides enough contact area to impededislodging of the stent assembly.

The invention further includes a delivery system for delivering a stentto a body lumen and expanding the stent, the delivery system comprisinga first axis, a second axis perpendicular to the first axis, anexpandable central balloon comprising first and second opposite sidesand centered on the intersection of the first and second axes, a firstexpandable side balloon positioned adjacent to the first side of thecentral balloon and centered on the first axis, and a second expandableside balloon positioned adjacent to the second side of the centralballoon and centered on the first axis, wherein a first width of thedevice measured along the first axis is greater than a second width ofthe device measured along the second axis.

In addition, the invention includes a compressible and expandabletubular stent comprising a first end, an opposite second end, and acentral portion between the first and second ends, wherein the centralportion comprises a reinforced area extending around at least a portionof a periphery of the stent.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained with reference to theappended Figures, wherein like structure is referred to by like numeralsthroughout the several views, and wherein:

FIG. 1 is a side view of one embodiment of a stent in accordance withthe invention, with the stent in its at least partially expandedcondition;

FIG. 2 is a top plan view of the stent of FIG. 1 with exemplary valveleaflets in their closed positions;

FIG. 3 is a front plan view of the stent of FIG. 1;

FIG. 4 is a schematic sectional view of a portion of the heart, with thestent of FIGS. 1-3 positioned within the annulus of the mitral valve;

FIG. 5 is a top schematic view of a mitral valve annulus with the stentof FIG. 2 positioned therein;

FIG. 6 is a front plan view of the stent of FIG. 3, with the stent shownin a compressed condition;

FIG. 7 is a front view of another embodiment of a stent in accordancewith the invention, with the stent shown in its at least partiallyexpanded condition;

FIG. 8 is a top plan view of the stent of FIG. 7;

FIG. 9 is a side view of the stent of FIG. 7;

FIG. 10 is a front view of the stent of FIG. 7, with the stent shown ina compressed condition;

FIG. 11 is a top schematic view of a mitral valve annulus with the stentof FIG. 8 positioned therein;

FIG. 12 is a front view of another embodiment of a stent in accordancewith the invention, with the stent in its at least partially expandedcondition;

FIG. 13 is a top plan view of the stent of FIG. 12;

FIG. 14 is a side view of the stent of FIG. 12;

FIG. 15 is a front view of another embodiment of a stent in accordancewith the invention;

FIG. 16 is a top plan view of the stent of FIG. 15 with valve leafletsin their closed positions;

FIG. 17 is a side view of the stent of FIG. 15;

FIG. 18 is a schematic sectional view of a portion of the heart, withthe stent of FIG. 15 positioned within the annulus of the mitral valve;

FIG. 19 is a front view of another embodiment of a stent in accordancewith the invention, including multiple flange portions;

FIG. 20 is a top plan view of the stent of FIG. 19;

FIG. 21 is a side view of a portion of an exemplary delivery system thatcan be used in the surgical implantation of the stents of the invention;

FIG. 22 is a top plan view of another exemplary delivery systempositioned within a stent of the invention;

FIG. 23 is a cross-sectional side view of a delivery system of the typeshown in FIG. 22;

FIG. 24 is a perspective view of another alternative embodiment of astent in accordance with the invention;

FIG. 25 is a schematic side view of the stent of FIG. 24 being expandedby a delivery system for positioning within a patient;

FIG. 26 is a top plan view of an exemplary two-barreled stent assemblyhaving non-circular stent shapes; and

FIG. 27 is a top plan view of an exemplary two-barreled stent assemblyhaving stents that have different sizes.

DETAILED DESCRIPTION

Referring now to the Figures, wherein the components are labeled withlike numerals throughout the several Figures, and initially to FIGS.1-3, one embodiment of a mitral stent assembly 10 in accordance with theinvention is illustrated. Although the stents of the invention, such asstent assembly 10, are described herein as being used for mitral valvereplacement, it is understood that many of the features of these stentscan be used for valves in other areas of the heart. For example, thestents of the invention may be used for replacement of the tricuspidvalve, where the configuration of such a stent may be identical orslightly different than described herein for replacement of the mitralvalve due to the different anatomy in that area of the heart. In anycase, the stents of the invention desirably restore normal functioningof a cardiac valve, and can be implanted percutaneously or usingsurgical techniques that include minimally invasive methods or moretraditional open-heart surgical methods.

Stent assembly 10 includes a first stent barrel 12 and a second stentbarrel 14, which are arranged so that a longitudinal axis 16 of stentbarrel 12 is generally parallel to a longitudinal axis 18 of stentbarrel 14, although the longitudinal axes 16, 18 may be at leastslightly angled relative to each other. Stent barrel 12 is attached tostent barrel 14 along at least a portion of its length at anintersection or common area 20. In this embodiment, stent barrel 12 istapered along its length, such that the stent barrel 12 is shorter at afirst edge 22 than at a second edge 24. As can be seen in FIGS. 1 and 2,first edge 22 is essentially the uppermost edge along the length of thestent barrel 12, and second edge 24 is the lowermost edge along thelength of the stent barrel 12 and on the opposite side of the barrel 12from the first edge 22. Stent barrel 12 further includes a tapered edge26 that extends from the first edge 22 to the second edge 24, which canbe a relatively straight or smooth slope when viewed from the side, asshown, or instead may be an edge that is curved or otherwise shapedbetween the edges 22, 24. For example, tapered edge 26 may essentiallybe either concave or convex in shape. Due to the spacing of the wiresfrom each other and the configuration of such wires, the tapered edge 26may be staggered, such as in a stair-step type of arrangement, ratherthan being smooth.

Because the stent barrel 12 is relatively cylindrical in shape, the edge26 can be considered to be curvilinear between the edges 22, 24 whenviewed in perspective. The length of second edge 24 may be only slightlylonger than the length of first edge 22, or may be considerably longer,depending on the patient anatomy and other factors, as will be describedin further detail below. The difference between the lengths of these twoedges 22, 24 will be a determining factor in the slope of the edge 26extending between them.

Stent barrel 14 of the stent assembly 10 is identical or nearlyidentical in size and shape to the stent barrel 12, and thus includes afirst edge 28 that is essentially the uppermost edge along the length ofthe stent barrel 14, which corresponds to the first edge 22 of stentbarrel 12. Stent barrel 14 further includes a second edge 30 that isessentially the lowermost edge along the length of the stent barrel 14and on the opposite side of the barrel 14 from the first edge 28, whichcorresponds to the second edge 24 of stent barrel 12. Stent barrel 14further includes a tapered edge (not visible in the illustrated views)that extends from the first edge 28 to the second edge 30 opposite itsfirst edge and generally corresponds to tapered edge 26 of stent barrel12. The tapered edge of stent barrel 14 is not visible in these Figures(e.g., FIG. 1), because it has approximately the same positioning (e.g.,length, angle, etc.) as the tapered edge 26 of stent barrel 12 and thusis obscured by the same features of stent barrel 12 in FIG. 1. However,it is contemplated that this edge, along with other features of thestent barrel 14, can be slightly or substantially different fromcorresponding features of the stent barrel 12 within a single stentassembly 10. This “double-barrel” arrangement of connected stentsprovides a stent arrangement that can at least roughly match the sizeand shape of the interior opening of the native valve in which it ispositioned.

The stent barrels of the invention, such as stent barrels 12, 14, asshown and described relative to the figures, can correspond generally toa stent of the type described in the above-cited Tower, et al. andBonhoeffer et al. references, for example, although it is understoodthat a wide variety of stent configurations can be used in accordancewith the invention. The stent barrels may be fabricated of platinum,stainless steel, Nitinol, an alloy of the type commercially availableunder the trade designation MP35N, or other biocompatible metal. Thestent barrels of the invention may alternatively be fabricated usingwire stock as described in the above-cited Tower, et al. applications,or the stent barrels may be produced by machining or laser cutting thestent from a metal tube, as is commonly employed in the manufacturing ofstents. The number of wires, the positioning of such wires, and variousother features of the stent can vary considerably from that shown in thefigures. The specifics of the stent barrels can vary widely within thescope of the invention, such that many other known generally cylindricalor cuff-like stent configurations may be used and are considered to bewithin the scope of the invention.

In any case, the stent barrels of the invention are preferablycompressible to a relatively small diameter for insertion into apatient, but are also at least slightly expandable from this compressedcondition to a larger diameter when positioned in a desired location inthe patient. It is further preferable that the process of compressingthe stent barrels does not permanently deform the stent barrels in sucha way that expansion thereof would be difficult or impossible. That is,each stent barrel should be capable of maintaining a desired structuralintegrity after being compressed and expanded. With the embodiments ofthe invention that include two barrels connected or attached to eachother, these manufacturing techniques may be modified to fabricate bothstents as an integral unit, if desired.

The stent barrels of the invention, like most expandable andcompressible cylindrical stents, generally take the form of a series ofzigzag or sinusoidal ring structures. These structures are coupledlongitudinally to one another to form a generally cylindrical-shapedstructure, although it is understood that the structures can be arrangedin an at least slightly oval or elliptical shape. Each ring structuretakes the form of a series of adjacent generally straight sections thatmeet one another at one end at a curved or angled junction to form a “V”or “U” shaped structure. It should also be understood that stent barrelsused according to the present invention may employ ring structurescoupled to one another at all or fewer than all of the bases of their“V”s, or coupled to one another by additional and/or differentstructures, such as longitudinal members of the type disclosed in U.S.Pat. No. 6,773,455, issued to Allen, et al., U.S. Pat. No. 6,641,609,issued to Globerman, and U.S. Pat. No. 6,136,023, issued to Boyle. Theinvention also includes within its scope stent barrels in which wiresare formed into zigzags and wound spirally to produce a cylindricalstructure, as in U.S. Pat. No. 6,656,219, issued to Wiktor, or wovenstents as disclosed in U.S. Pat. No. 4,655,771, issued to Wallsten.

Stent barrels of the type described above can be assembled into a mitralor tricuspid stented valve assembly in accordance with the methods ofthe invention described herein. One exemplary method for assembling astented valve generally first includes preparation of a vein segment,then a subsequent mounting or attachment of the prepared vein segment tothe stent, using a variety of mounting or attachment techniques. FIG. 2illustrates the stent assembly 10 with a three-leaflet valve 32, 34positioned within each of the stent barrels 12, 14, respectively. Thisthree-leaflet arrangement is exemplary; alternative configurationsinclude a bi-leaflet valve positioned in both of the stent barrels, andvalves that are different from each other in each of the stent barrels(e.g., one of the stent barrels includes a three-leaflet valve while theother barrel includes a bi-leaflet valve). In any case, themulti-barreled stent configurations of the invention advantageouslyallow for replacement of only one of the valves if there is a valvefailure at some point after implantation, while the properly functioningvalve remains operational.

The stent assemblies of the invention may use a preserved bovine jugularvein of the type described in the above-cited Bonhoeffer, et al. andTower, et al. references. However, other vessels or donor species mayalternatively be used, and in order to provide additional valve strengthin the relatively high-pressure conditions that exist in the mitralvalve area of the heart, pericardial valves, polymeric valves, ormetallic valves may alternatively be used in a tricuspid or bicuspidleaflet configuration.

FIG. 6 illustrates the stent assembly 10 with stent barrels 12, 14 in anat least partially compressed condition. The stent barrels 12, 14 may becompressed in this manner prior to implantation in a patient, forexample, and can be expanded into the mitral or tricuspid valve spaceduring the surgical procedure.

As described above, stent barrels 12, 14 are connected to or extend fromeach other at common area 20. The stent barrels may be connected alongtheir entire lengths at the common area 20, or may instead be attachedalong only a portion of their lengths. In one exemplary embodiment, thestent barrels 12, 14 may be manufactured as separate components, thenbonded, adhered, welded, or otherwise attached to each other at one ormore points along the length of common area 20. In order to provideadditional flexibility between the stent barrels 12, 14, they may beattached or intertwined with each other a limited number of the rows ofstent wires. Alternatively, to provide less flexibility between thestent barrels 12, 14, they may be attached or intertwined at every pointwhere they contact or are otherwise adjacent to each other along theirlengths. In another example, the stent barrels 12, 14 may bemanufactured or assembled in such a way that the wires of the stentbarrels 12, 14 are woven to intersect or connect in this area during theformation of those two barrels. In this embodiment, the barrels 12, 14are formed as portions of an integrated wire structure and therefore arenot formed as separate components that need to be attached or secured toeach other. In yet another example, two separate stent barrels arepositioned in a desired location relative to each other, then a separatedevice or structure, such as a mechanical strut, is positioned forattachment to both stent barrels, thereby connecting them to each otherin a double-barrel system of the type shown.

As shown in the figures and as is briefly described above, first edge 22of stent barrel 12 is shorter than second edge 24 of stent barrel 12.The lengths of these two portions are designed to be different in orderto accommodate certain anatomical structures, which are described withfurther reference to FIGS. 4 and 5.

FIG. 4 illustrates a portion of a heart 40, with a stent assembly 10 ofthe invention positioned therein. In particular, heart 40 includes aleft atrium 42, a left ventricle 44, a mitral valve 46 and an aorticvalve 48. The broken lines of mitral valve 46 illustrate its nativeleaflets as they would generally be configured in a closed positionprior to implantation of stent assembly 10. In particular, mitral valve46 includes a first leaflet 50 on the anterior side of the valve, and asecond leaflet 52 on the posterior side of the valve. When mitral valve46 is operating properly, the native leaflets 50, 52 will generallyfunction in such a way that blood flows toward the left ventricle 44when the leaflets 50, 52 are in an open position, and so that blood isprevented from moving toward the left atrium 42 when the leaflets 50, 52are in a closed position. However, stent assembly 10 can be positionedin the area of mitral valve 46 when it is not functioning properly (toreplace the mitral valve) in accordance with the invention, therebypushing the leaflets 50, 52 out of the mitral valve space, such as areshown as leaflets 56 and 58, respectively. In this view, first stentbarrel 12 is visible; however, the second stent barrel 14 would bepositioned immediately behind stent barrel 12.

In this embodiment, first edge 22 of stent barrel 12 is positioned tomove leaflet 50 on the anterior side of the valve out of the mitralvalve space and to its position shown as leaflet 56, and second edge 24of stent barrel 12 is positioned to move leaflet 52 on the posteriorside of the valve out of the mitral valve space and to its positionshown as leaflet 58. In order to not block the flow of blood through theaortic valve 48, the first edge 22 of stent barrel 12 is provided with alength that is sufficiently short so that it does not push the leaflet56 to a position in which it will interfere with blood flow through theaortic valve 48 and/or interfere with the actual movement or functioningof the leaflets of the aortic valve 48. However, first edge 22 of stentbarrel 12 further is provided with a sufficient length to provide asuitable area of contact with the annulus of the mitral valve to help tomaintain it in its desired position. Thus, as shown, one embodiment ofthe stent barrel 12 includes a top portion that extends into the leftatrium 42 and a lower portion that moves the leaflet 36 out of themitral valve space, yet allows a portion of leaflet 36 to extend freelybeyond the first edge 22. The amount of the leaflet 56 that extendsbeyond the bottom of stent barrel 12 is preferably small enough that itdoes not substantially and/or detrimentally interfere with thefunctioning of the aortic valve 48. It is noted that the structure,features, and positioning of the stent barrel 14 of the stent assembly10 can be similar or identical to that of stent barrel 12.

FIGS. 7-11 illustrate another exemplary embodiment of a stent assembly60 of the invention, which includes a first stent barrel 62 and a secondstent barrel 64, which are arranged so that a longitudinal axis 66 ofstent barrel 62 is generally parallel to a longitudinal axis 68 of stentbarrel 64. Stent barrel 62 is connected to stent barrel 64 along atleast a portion of its length at a common area 70. In this embodiment,stent barrel 62 is not tapered along its length, but instead extends asa continuous cylinder shape from its first end 72 to its second end 74.Similarly, stent barrel 64 is not tapered along its length, but insteadextends as a continuous cylinder shape from a first end 76 to a secondend 78. As shown in the figure, the distance between first and secondends 72, 74 is greater then the distance between first and second ends76, 78 so that the first stent barrel 62 is longer than the second stentbarrel 64. The diameters of the first and second stent barrels 62, 64can be essentially the same as each other when expanded, or may bedifferent, depending on the anatomy of the patient in which the stentassembly will be implanted, the implantation techniques used, and otherfactors.

As is shown best in FIG. 7, the second end 74 of first stent barrel 62is generally aligned with the second end 78 of second stent barrel 64,while first end 72 of first stent barrel 62 is offset relative to thefirst end 76 of second stent barrel 64; however, it is contemplated thatthe second ends 74, 78 of these stent barrels are not aligned, butinstead are also offset from each other. In other words, stent barrel 64can be positioned in a different relative location along the length ofstent barrel 62 in such a way that none of the ends of the stent barrels62, 64 are aligned with each other.

FIG. 11 illustrates stent assembly 60 positioned within the annulus ofan exemplary mitral valve 80. In this configuration, the shorter stentbarrel 64 is adjacent to an anterolateral portion 84 of mitral valve 80and the longer stent barrel 62 is adjacent to a posteromedial portion 82of mitral valve 80. In this way, interference of the stent assembly 60with the functioning of the aortic valve and left ventricular outflowtract will be minimized, in accordance with the invention. Thus, thestent barrel 64, which is adjacent to the anterolateral portion 84 ofthe mitral valve 80, preferably is sufficiently short to minimizeinterference with the functioning of the aortic valve, yet issufficiently long to provide enough contact area between the barrel 64and the annulus to lessen the chances that the stent assembly 60 willbecome dislodged once it has been implanted. The stent barrel 62, whichis adjacent to the posteromedial portion 82 of the mitral valve 80, canhave any appropriate length that provides sufficient contact area withthe annulus to lessen the chance that the stent assembly 60 will becomedislodged once it has been implanted.

Similarly, if the stents of the invention are positioned within theannulus of a triscuspid valve, the shorter barrel (e.g., stent barrel 64of FIG. 7) or the shorter side of a tapered barrel (e.g., first edge 22of stent barrel 12 of FIG. 1) is preferably aligned with or adjacent tothe anterior annulus of the tricuspid valve and/or the septal annulus ofthe tricuspid valve and/or the anteroseptal commissure of the tricuspidvalve.

FIG. 10 illustrates stent assembly 60 with the first and second stentbarrels 62, 64 in their compressed conditions. In order to insert thestent assembly 60 into the patient's heart, the stent assembly maydesirably be compressed to such a condition in order to aid in lessinvasive surgical techniques. When the stent assembly 60 is compressed,stent barrels 62, 64 may lengthen at least slightly as compared to theiruncompressed or expanded states, or may remain essentially the samelength, depending on the construction of the stent barrels 62, 64.Exemplary devices and methods for delivering the stent assembly in sucha compressed condition will be explained in further detail below.

It is also contemplated that one or both of the first and second stentbarrels 62, 64 can include a tapered edge, a flared edge, or the like,such as is discussed above relative to edge 26 of FIGS. 1-5. For oneexample, a stent assembly may include two stent barrels having differentlengths, where the shorter barrel is additionally provided with atapered edge to further minimize interference with the leaflet that isclosest to the aortic valve. Alternatively, both of the stent barrelscould have tapered edges, even if they have different lengths.

FIGS. 12-14 illustrate another exemplary embodiment of a stent assembly90 of the invention, which includes a first stent barrel 92 and a secondstent barrel 94 that are connected or extend from each other along atleast a portion of their lengths. As with the embodiment of FIG. 7, thefirst stent barrel 92 is longer than the second stent barrel 94;however, in this embodiment the second stent barrel 94 is proportionallyeven shorter relative to the first stent barrel 92 as compared to thelength relationship between the stent barrels 62, 64 of stent assembly60. That is, the difference between the lengths of the barrels isgreater than in the embodiment of FIG. 7. Otherwise, this embodiment ofstent assembly 90 is substantially the same as that of the stentassembly 60, and the same variations and options described above arealso contemplated for this embodiment. The differences in the lengths ofthe two stent barrels within a particular stent assembly of theinvention may be greater or smaller than that shown in the Figures.

The stent assemblies described herein that include more than one stentbarrel are generally shown and described as including stent barrels thatare cylindrical, oval, or elliptical in shape; however, a number ofdifferent stent shapes are also contemplated. One exemplary alternativeconfiguration is illustrated in FIG. 26 with stent assembly 250, whichincludes a first stent barrel 252 and a second stent barrel 254. Each ofthese two stent barrels has a curvilinear surface (which can be designedto generally match the shape of the ends of the annulus of a mitralvalve) and a generally flat or planar surface that results in more“squared off” corners where the flat surface meets the curvilinearsurface. The flat surfaces of the stent barrels 252, 254 are attached orextend from each other at a central area 256. This arrangement providesmore potential connection points between the two stent barrels since thesurface area of contact is larger than is provided when two cylindricalstents are brought in contact with each other.

Another exemplary configuration is illustrated in FIG. 27 with stentassembly 260, which includes a first stent barrel 262 and a second stentbarrel 264, where the second stent barrel 264 is larger than the firststent barrel 262. In addition, each of these stent barrels is shown toinclude a portion that is somewhat flat and in contact with a flatportion of the other stent barrel, although it is also contemplated thatthese stent barrels have curvilinear surfaces that are in contact witheach other, basically along a tangent line. With this embodiment andothers described herein, it is possible to insert each of the two ormore stent barrels separately into the patient, and then attach them toeach other while they are inside the patient. The attachment between thestent barrels can be accomplished through the use of cooperatingmechanical attachment (e.g., barbs, hooks, or the like), magneticattraction, adhesives, or other methods that allow for permanent orsemi-permanent attachment of the stent barrels to each other. Withcontinued reference to FIG. 27, it is also contemplated that a firststent barrel (e.g., stent barrel 264) can be inserted into the patientand expanded to a first outer perimeter that is relatively large, andthen a second stent barrel (e.g., stent barrel 262) is inserted adjacentto the first stent barrel and expanded so that the expansion of thesecond stent barrel causes at least a slight compression of the firststent barrel. The two stent barrels can be attached to each other eitherbefore, during, or after expansion of the second stent barrel

FIGS. 15-18 illustrate yet another embodiment of a stent assembly of theinvention. In particular, a stent assembly 100 is shown, which includesa single stent barrel 102. The single barrel device can be used in anative valve, in a valve previously repaired with an annuloplasty bandor ring, or in a valve replaced with a bioprosthetic device. Stentbarrel 102 is tapered along its length, similar to the stent barrelsdescribed above relative to FIGS. 1-5. In particular, stent barrel 102is shorter at a first edge 104 than at a second edge 106, wherein firstedge 104 is shown as the uppermost edge along the length of stent barrel102, and second edge 106 is shown as the lowermost edge along theopposite side of the barrel 102 from the first edge 104. Stent barrel102 further includes a tapered edge 108 that extends from the first edge104 to the second edge 106. Edge 108 can be relatively straight orsmooth when viewed from the side, as shown, or instead may be an edgethat is curved or otherwise shaped between the edges 104, 106. Due tothe spacing of the wires from each other and the configuration of suchwires, the tapered edge 108 may be staggered, such as in a stair-steptype of arrangement, rather than being smooth. Because the barrel 102 isrelatively cylindrical in shape, the edge 108 is actually curvilinearbetween the edges 104, 106 when viewed in perspective. The length ofsecond edge 106 may be only slightly greater than the length of firstedge 104, or may be considerably longer, or even be equal in length, asdesired and/or depending on the patient anatomy. This stent assembly 100includes only a single stent barrel as compared to the dual-barrelembodiments described above; however, the tapered edge provides certainsimilar advantages to those of the dual-barrel design.

As with the stent assembly 10 described above, the lengths of these twoedges 104, 106 of stent assembly 100 are designed to be different inorder to accommodate certain anatomical structures, which are describedwith further reference to FIG. 18. This figure illustrates a portion ofa heart 110, with a stent assembly 100 of the invention positionedtherein. In particular, heart 110 includes a left atrium 112, a leftventricle 114, a mitral valve 116, and an aortic valve 118. The brokenlines of mitral valve 116 illustrate its leaflets as they wouldgenerally be configured prior to implantation of stent assembly 100. Inparticular, mitral valve 116 includes a first leaflet 120 on theanterior side of the valve, and a second leaflet 122 on the posteriorside of the valve.

Stent assembly 100 can be positioned at the area of mitral valve 116when it is not functioning properly (to replace the mitral valve),thereby pushing the first and second native leaflets 120, 122 out of themitral valve space, such as are shown as leaflet 124 and 126,respectively. As shown, first edge 104 is positioned to move leaflet 120on the anterior side of the valve out of the mitral valve space and toits position shown as leaflet 124, and second edge 106 of stent barrel102 is positioned to move leaflet 122 on the posterior side of the valveout of the mitral valve space and to its position shown as leaflet 126.In order to not block the flow of blood through the aortic valve 118,the first edge 104 of stent barrel 102 is provided with a length that issufficiently short so that it does not push the leaflet 124 to aposition in which it will interfere with blood flow through the aorticvalve 118 and/or interfere with the actual movement or functioning ofthe leaflets of the aortic valve 118; however, first edge 104 is furtherprovided with a sufficient length to provide a suitable area of contactwith the annulus of the mitral valve to help to maintain it in itsdesired position. Thus, as shown, one embodiment of the stent barrel 102includes a top portion that extends into the left atrium 112 and a lowerportion that moves the leaflet 124 out of the mitral valve space, yetallows a portion of leaflet 124 to extend freely beyond its lower edge.The amount of the leaflet 124 that extends beyond the bottom of stentbarrel 102 is preferably small enough that it does not substantiallyand/or detrimentally interfere with the functioning of the aortic valve118.

Stent barrel 102, along with any of the other stent barrels of thepresent invention, may be configured so that they are relativelycircular in cross section when in their expanded condition, as shown inthe Figures. However, it is also possible that the stent barrels of theinvention are at least slightly elliptical, oval, D-shaped, square, ordifferently shaped in cross-section when in their expanded condition. Inthe case of the single barrel design of the stent assembly 100, such anon-circular shape may be provided for the stent barrel in order toaccommodate the shape of the mitral valve annulus, for example. That is,the shape of the stent assemblies can be designed and selected toprovide both positional stability and a proper fit to the patient'sanatomy.

To make the stent barrel 102 into a stented valve that can be used toreplace the mitral valve, one or more valve segments are attached withinthe stent barrel 102 using techniques known in the art for attachingvalve segments within a stent. For example, FIG. 16 illustrates stentassembly 100 with a two-leaflet valve 101 positioned within stent barrel102. In the case of such a two-leaflet valve, the leaflets may beattached in a generally central location in order to prevent prolapse ofthe leaflets into the atrium. However, another leaflet configuration mayalternatively be used, such as a three-leaflet valve.

If more than one valve segment is to be attached within a single stentbarrel, the multiple valve segments may further be attached to eachother where they are adjacent to each other in the stent assembly.Alternatively, the stent barrel may be provided with a center strut orsupport portion that spans across the open portion of the stent barrel,thereby dividing the center portion into two generally “D” shaped areasinto which valve segments can be attached, for example. These areas canbe the same or a different size and shape from each other, depending onwhere the center strut or support portion is positioned.

FIGS. 19 and 20 illustrate a docking or positioning feature that canoptionally be used with any of the stent barrels of the invention, andis shown with particular use on a stent assembly 140. Stent assembly 140includes a first stent barrel 142 and a second stent barrel 144 that islonger than the first stent barrel 142. First stent barrel 142 includesa first end 146 and a second end 148, and second stent barrel 144includes a first end 150, which is generally aligned with the first end146 of stent barrel 142, and a second end 152, which is offset from thesecond end 148 of first stent barrel 142. First stent barrel 142 furtherincludes at least one flange portion 154 extending from the stentstructure at the first end 146. In the exemplary embodiment shown, oneflange portion 154 extends from all or most of the points of each “V”structure at the first end 146, although it is contemplated that thestent barrel 142 include any number of flange portions 154. These flangeportions 154 may be made of the same wire-type material from which thestent barrel 142 is made, and the flanges may be integrally molded orformed with the stent assembly 140. Alternatively, the flange portions154 may be made of a different material and/or may comprise separatestructures that are attached or connected to the structure of stentbarrel 142. The flange portions 154 may also have a different size orshape than the triangular or V-shaped structures illustrated. Forexample, the flange portions 154 may be semi-circular, rectangular,oblong, or the like, and may be considerably smaller or larger thanshown. In yet another variation, a different flange structure can beprovided that is more continuous around the periphery of the stentbarrel 142 (i.e., does not comprise a series of adjacent flanges).

In addition to or as an alternative to the flange portions 154 providedon the stent barrel 142, the second stent barrel 144 may include atleast one flange portion 156 extending from the stent structure at itsfirst end 150. The features and configurations described above relativeto flange portions 154 are also contemplated for use with the flangeportion(s) 156. These flange portions 156 may be the same as ordifferent than the flange portions 154 in structure, shape, size, andthe like, depending on the particular configuration and use of the stentassembly 140.

In any case, the flange portion(s) 154 and/or 156 are preferablyconfigured to be shaped and sized to provide an anchoring function forthe stent assembly 140 when it is positioned to replace a valve.Referring to FIG. 4, for example, if stent assembly 140 were positionedwithin the mitral valve annulus in a similar manner to how stentassembly 10 is positioned within heart 40, any flange portions thatextend from the stent assembly 140 can provide interference with thewalls of the left atrium 42, thereby inhibiting motion of the stentassembly 140.

Any of the stent assemblies discussed herein can further includestructures that provide a fixation function for securing the stentassembly in its desired location. For example, the stent assembly caninclude hooks, barbs, or the like that attach to a valve annulus upondeployment of the stent assembly.

The stent assemblies of the invention may further include a cover orother material to prevent blood leakage into undesired areas of theheart. For example, the stent assemblies that include two stent barrelsmay include a cover (e.g., tissue, polymer, or biocompatible fabric)that spans the area between the barrels on one or both sides of thestent assembly and/or covers the entire outer periphery of the stentbarrels. Such a cover 98 is illustrated in broken lines in FIG. 13, andis shown on both sides of the stent assembly 90.

Any of the stent assemblies described above can be used for percutaneousinsertion and implantation of a replacement heart valve in replacementof a defective or malfunctioning valve. A portion of an exemplary system130 that can be used to implant a double-barrel stent of the typesdescribed above is illustrated in FIG. 21. System 130 includes anelongated balloon catheter having two inflatable balloons 132, 134 thatare separated from each other near the distal end of the system 130.Balloons 132, 134 are connected for fluid communication with separatelumens that extend through the length of the catheter. These lumensprovide for independent inflation and deflation of the balloons 132, 134with a fluid, such as a radio-opaque fluid, during the process ofdeploying a stent assembly within a patient. System 130 further includesa thin guide wire 136 that extends generally along the length of thecatheter. The guide wire 136 may be, for example, a 0.089 cm diameterextra stiff guidewire as manufactured by Amplatzer of Golden Valley,Minn., which may be used in a conventional manner to guide the catheterto its desired implant location.

System 130 may be at least partially disassembled for loading of a stentassembly onto the balloons 132, 134. For example, a connector 138, whichextends generally from one end of balloons 132, 134 and is attached tothe guide wire 136 at its opposite end, can be disconnected from theguide wire to provide two separate balloons 132, 134 onto which twobarrels of a double-barreled stent can be positioned. The stent barrelsmay then be crimped or compressed around the balloons 132, 134 untilthey are the desired size for implanting into a patient, and theconnector 138 can then be reattached to the guide wire 136 and thesystem 130 can be inserted into the patient. When the components of thesystem 130 are positioned relative to the mitral valve area of thepatient, balloons 132, 134 may be inflated to thereby expand thecompressed stent barrels to the desired size relative to the mitralvalve annulus. After such stent expansion is complete, the balloons 132,134 can be deflated and the system 130 can then be withdrawn from thepatient.

System 130 may further include one or more elongated sheaths (not shown)positioned over the catheter, which are large enough to surround one orboth compressed sheaths when they are located over the balloon 132, 134.In their open or deployed configurations, each sheath is positionedalong the catheter length so that balloons 132, 134 are not constrainedand are therefore able to be inflated. Sliding each sheath toward thedistal end of the system 130 so that it covers one or both balloonswould provide a closed position of the device 10, which is theconfiguration in which the device would typically be inserted into apatient.

As discussed above, at least one embodiment of the present inventionincludes a stent assembly having a single barrel, such as is shown inFIGS. 15-18, for example. If such a single-barreled stent is to beimplanted into a body opening that is not circular in shape, oneexemplary delivery and stent-expansion device 200 that can be used forimplantation of the stent is illustrated in FIGS. 22 and 23. Device 200generally includes a multi-balloon structure consisting of a centralballoon 202, two side balloons 204, 206, and an outer balloon 208.Because the side balloons 204, 206 are located on opposite sides ofcentral balloon 202, the width of the device 200 along a first axis 210is larger than the height of the device 200 along a second axis 212 thatis generally perpendicular to the first axis 210. This type ofarrangement is particularly adaptable to a stent that has a generallyelliptical or oval shape, such as may be used in the replacement of amitral valve, although it can be used for other stent opening shapes.

The relative sizes of the multiple balloons may vary from thearrangement shown, depending on the shape and size of the stent in whichthe device 200 will be positioned. For example, in order to achieve anelliptical shape, the side balloons 204, 206 will preferably be at leastslightly smaller than the central balloon 202. However, if the shape ofthe stent is not elliptical, the side balloons 204, 206 may be roughlythe same size as the central balloon 202 and/or each of the sideballoons 204, 206 may be identically or differently sized and shaped asthe other of the side balloons 204, 206. The three balloons 202, 204,206 can be independently expandable or may be connected to each otherfor simultaneous expansion of all the balloons. To provide morecustomizable balloon inflation, the balloons 202, 204, 206 will havetheir own inflation controls, which can be particularly useful to allowa surgeon to adjust the expansion of the stent in which it is beingused. Whether or not the balloons 202, 204, 206 are independentlyinflatable, these inner balloons are preferably expanded prior toinflation of the outer balloon 208. That is, the balloons 202, 204, 206are first inflated to expand a stent to its desired shape and size, thenthe outer balloon 208 is inflated to essentially “lock” or seal thestent in place. Due to the configuration of the inner balloons 202, 204,206, the outer balloon 208 will generally conform to the outermostbounds of the inner balloons, thus maintaining a shape that is notcircular. However, the outer balloon 208 provides additional pressureagainst the inside of the stent, such as stent 214 in FIG. 22, to keepthe stent in its desired location. Once the stent is expanded, theballoons 202, 204, 206, 208 can be deflated and removed from the stent.

While the description of the device 200 includes three inner balloonsand one outer balloon, it is contemplated that the delivery devices ofthe invention may include more or less than three inner balloons and/orthat the inner balloons may be positioned differently than shown anddescribed. Further, the outer balloon (e.g., balloon 208) may not beincluded as part of the delivery device, if desired. In anotheralternative, more than one outer balloon may be used to encompass someor all of the inner balloons. As with other delivery systems of theinvention, the delivery device 200 may use fluids for inflation of theballoons, such as a radio-opaque fluid, during the process of deployinga stent assembly within a patient.

FIGS. 24 and 25 illustrate another embodiment of a stent 220 having asingle barrel construction. Stent 220 is shown as having a generallycircular shape; however, other shapes for the stent are alsocontemplated, such as elliptical, oval, or another shape thatcorresponds with an implantation site in a patient. Stent 220 includes aseries of wires arranged as multiple zigzag structures having adjacentgenerally straight sections that meet one another at a curved or angledjunction to form a “V” or “U” shaped structure, although other wirearrangements are contemplated. In any case, stent 220 includes areinforced area 222, which may be provided through the use of a wirethat is thicker than the remaining wires in the structure, for example.Alternatively, reinforced area 222 may be provided as another structuremade of the same or a different material than the other wires of thestent 220, where the reinforced area 222 will be relatively stiff and/orconstrained as compared to the areas above and below reinforced area222. For example, the reinforced area 222 may include a sealing gasket,such as tissue, fabric, polymer, metal mesh, or the like. In this way,the stent 220 can be designed so that the area 222 is the desired sizefor the annulus in which it will be positioned, while allowing the areasabove and below the area 222 to expand or flare to a larger size to helpto anchor the stent 220 in place. In addition, the stent 220, or any ofthe embodiments of stents described herein relative to the invention(including double-barreled stents), may include a gasket or other memberaround its exterior to provide for sealing against paravalvular leakageand to facilitate pannus in-growth for stabilization of the stent. Sucha gasket or other member may alternatively or additionally be positionedon the interior portion of the stent or on the underside of a cuffprovided on the stent.

FIG. 25 illustrates an exemplary delivery system for expanding the stent220 as described above. In particular, the delivery system includes oneor more balloons, where a balloon or portion of a balloon 224 ispositioned on one side of the stent 220 and a balloon or portion of aballoon 226 is positioned on the opposite side of the stent 220. Asshown, the stent 220 is relatively smaller in diameter at its reinforcedor central area 222 than at the flared areas near the top and bottom ofthe stent 220. Thus, the balloon portions 224, 226 are relativelyexpandable to provide the necessary pressure to push the stent outwardlyin this manner.

The stent assemblies of the present invention may be positioned withinthe desired area of the heart via entry in a number of different ways.In one example, the stent assembly may be inserted transatrially, whereentry may be done either percutaneously or in a minimally invasivetechnique on a beating heart in which access is through the side of theheart, or even through a standard open heart valve replacement procedureusing heart-lung bypass and sternotomy where the described device wouldbe used as an alternative to the standard replacement. In anotherexample, the stent assembly may be inserted transapically, where entryagain may be done either percutaneously or in a minimally invasivetechnique on a beating heart in which access is through the side of theheart. In yet another example, the stent assembly may be insertedtranseptally, where entry can be done percutaneously, such as via thevenous system into the right atrium and across a small hole in theseptum to enter the left atrium. It is also possible that the deliveryapproaches may include balloons that would be used to facilitate thecrossing of the mitral valve, thereby avoiding entanglement in themitral apparatus.

Although the description of the stent barrels herein is primarilydirected to stents that are expanded through pressure from an expandableballoon positioned therein, it is also contemplated that the stentbarrels of the present invention are self-expanding such that pressureis required to maintain the stent in its compressed condition, andremoval of such pressure will allow these stents to expand to theirdesired size. In these cases, the delivery system will be somewhatdifferent than that described above relative to stents that are notself-expanding, and will instead include a system that only requiresremoval of external pressure (e.g., a compressive sheath) to allow thestents to expand, such as is the case with the delivery of stent graftsfor aneurysms in the ascending aorta. These systems may also incorporatemeans for recapturing and/or repositioning the stent, if desired. In anycase, it may be desirable to measure the mitral valve area with sometype of spacer prior to installing the actual stent assembly in theheart of the patient.

The stent assemblies of the invention may further include a means offacilitating orientation of the assembly, which can be particularlyadvantageous in cases where the stent assemblies include asymmetricfeatures and configurations that must be properly oriented relative tothe anatomy of the patient. To that end, the stent assemblies mayinclude portions with materials that are opaque when viewed with variousimaging techniques, such as echogenic coatings and radiopaque metals andpolymers. Additionally or alternatively, the material used to fabricatethe stent itself may be highly visible when using certain imagingtechniques so that the user has a clear visibility of the orientation ofthe device prior to and during deployment.

The present invention has now been described with reference to severalembodiments thereof. The foregoing detailed description and exampleshave been given for clarity of understanding only. No unnecessarylimitations are to be understood therefrom. It will be apparent to thoseskilled in the art that many changes can be made in the embodimentsdescribed without departing from the scope of the invention. Thus, thescope of the present invention should not be limited to the structuresdescribed herein.

What is claimed is:
 1. A compressible and expandable stent assembly forimplantation in a body lumen, the stent assembly comprising: a firststent barrel including: a first tubular structure that is compressibleand expandable in a radial direction, a first lumen extending throughthe first tubular structure extending from a first open end of thetubular structure to a second open end of the tubular structure, whereina first central longitudinal axis is defined by the first lumen, a firstinner luminal surface, and a first outer surface having a firstperiphery wherein the second open end of the first stent barrel istapered; a second stent barrel including: a second tubular structurethat is compressible and expandable in a radial direction, a secondlumen extending through the second tubular structure extending from afirst open end of the second tubular structure to a second open end ofthe second tubular structure, wherein a second central longitudinal axisis defined by the second lumen, a second inner luminal surface, and asecond outer surface having a second periphery, wherein the second openend of the second stent barrel is tapered; a first prosthetic valvedisposed within the first lumen of the first stent barrel; and a secondprosthetic valve disposed within the second lumen of the second stentbarrel, wherein the first longitudinal axis is generally parallel to thesecond longitudinal axis, wherein the first stent barrel is fixed to thesecond stent barrel along a common area of the first outer surface andthe second outer surface defining a first tangential line parallel tothe first and second longitudinal axes along each of the first andsecond stent barrels such that first stent barrel has a fixed positionrelative to the second stent barrel that is maintained in both adelivery configuration and a deployed configuration.
 2. The stentassembly of claim 1, wherein the first and second stent barrels eachcomprise a series of wires that are woven together along the firsttangential line.
 3. The stent assembly of claim 1, wherein the first andsecond stent barrels comprise separate components that are mechanicallyconnected to each other along at least a portion of their lengths. 4.The stent assembly of claim 1, wherein a portion of at least one of thefirst and second stent barrels is cylindrical.
 5. The stent assembly ofclaim 4, wherein the first and second stent barrels have generally thesame cross-sectional shape and size.
 6. The stent assembly of claim 1,wherein the first stent barrel has a different cross-sectional shapethan the second stent barrel.
 7. The stent assembly of claim 1, whereinthe first stent barrel includes at least one flange portion extending atan angle from the first open end thereof.
 8. The stent assembly of claim7, wherein the at least one flange portion comprises a series ofadjacent structures spaced from each other around at least a portion ofthe first periphery of the first stent barrel at the first open end. 9.The stent assembly of claim 7, wherein the second stent barrel includesat least one flange portion extending at an angle from the first openend thereof.
 10. The stent assembly of claim 1, wherein the first andsecond stent barrels are radially expandable by a balloon catheter. 11.The stent assembly of claim 1, wherein the first and second stentbarrels are radially self-expandable.
 12. The stent assembly of claim 1,wherein the first stent barrel includes a first outer diameter in thedeployed configuration and the second stent barrel includes a secondouter diameter in the deployed configuration, wherein the first outerdiameter and the second outer diameter are equal.
 13. The stent assemblyof claim 1, wherein the first prosthetic valve comprises a plurality ofleaflets.
 14. The stent assembly of claim 13, wherein the secondprosthetic valve comprises a plurality of leaflets.